Electrode Assembly For Catheter System

ABSTRACT

In an electrode assembly for a catheter system, a plurality of struts extends from a proximal end to a distal end of the electrode assembly. Each strut has a longitudinally extending proximal leg, a longitudinally extending distal leg, and a center segment extending between and interconnecting the proximal leg and the distal leg. A hinge interconnects the proximal leg and the center segment, and another hinge interconnects the distal leg and the center segment. The center segment of each of the struts has a corresponding electrode thereon. The electrode assembly is configurable between a collapsed configuration and an expanded configuration, with the electrodes being transversely spaced from the longitudinal axis of the electrode assembly a greater distance in the expanded configuration than in the collapsed configuration.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to provisional application Ser. No.61/842,646 filed Jul. 3, 2013, the entire specification of which isincorporated herein.

BACKGROUND OF THE DISCLOSURE

A. Field of the disclosure

The present disclosure relates generally to a catheter system for use ina human body, and more particularly to a multi-electrode cathetersystem, and even more particularly to an electrode assembly for amulti-electrode catheter system.

B. Background Art

Catheter systems are well known in the art for use in medicalprocedures, such as diagnostic, therapeutic and ablative procedures.Typical catheter systems generally include an elongate catheterextending from a handle. A physician manipulates the catheter throughthe patient's vasculature to an intended site within the patient. Thecatheter typically carries one or more working components, such aselectrodes or other diagnostic, therapeutic or ablative devices forcarrying out the procedures. One or more controls or actuators may beprovided on the handle for selectively adjusting one or morecharacteristics of the working components.

One particular example of a multi-electrode catheter system is anablative catheter system in which the working component is amulti-electrode component carried at the distal end of a flexiblecatheter. A control wire extends within the catheter from themulti-electrode component to the handle to operatively connect themulti-electrode component to an actuator on the handle. Manipulating theactuator acts on the control wire to configure the multi-electrodecomponent into a desired configuration for carrying out the ablativeprocedure. For example, in one such ablative catheter system made by St.Jude Medical, Inc. under the trade name EnligHTN, the multi-electrodecomponent is an electrode assembly in the general form of a basket. Uponlocating the electrode basket at a desired location within the patient,manipulating the actuator associated with the handle pulls on thecontrol wire to reconfigure the electrode basket from a collapsedconfiguration to an expanded configuration in which the electrodes areintended to be in apposition with a surface, such as an arterial wall ofthe patient. It is thus desirable to facilitate apposition of as many ofthe electrodes of the electrode basket as possible against the arterialwall of the patient when the electrode basket is expanded to achieveoptimal performance of the multi-electrode catheter system.

BRIEF SUMMARY OF THE DISCLOSURE

In one embodiment, an electrode assembly for an electrode cathetersystem generally comprises first and second struts each extending from aproximal end to a distal end of the electrode assembly and having acorresponding electrode disposed thereon intermediate the proximal anddistal ends of the electrode assembly. The electrode assembly isconfigurable between a collapsed configuration and an expandedconfiguration, with the electrodes being transversely spaced from thelongitudinal axis of the electrode assembly a greater distance in theexpanded configuration than in the collapsed configuration. In thecollapsed configuration, the electrode on the first strut is at a firstlongitudinal position intermediate the proximal and distal ends of theelectrode assembly and the electrode on the second strut is at a secondlongitudinal position intermediate the proximal and distal ends of theelectrode assembly and different from the first longitudinal position ofthe electrode on the first strut. In the expanded configuration, thefirst longitudinal position of the electrode on the first strut issubstantially equal to the second longitudinal position of the electrodeon the second strut.

In another embodiment, an electrode assembly for an electrode cathetersystem generally comprises a plurality of struts each extending from aproximal end to a distal end of the electrode assembly. Each strut has alongitudinally extending proximal leg, a longitudinally extending distalleg, and a center segment extending between and interconnecting theproximal leg and the distal leg. The proximal leg and the distal leg ofat least one of the struts has a corresponding stiffness, and the centersegment of the at least one of the struts has a stiffness greater thanthe stiffness of each of the proximal leg and the distal leg of the atleast one of the struts. The center segment of each of the struts has acorresponding electrode thereon. The electrode assembly is configurablebetween a collapsed configuration and an expanded configuration, withthe electrodes being transversely spaced from the longitudinal axis ofthe electrode assembly a greater distance in the expanded configurationthan in the collapsed configuration.

In yet another embodiment, an electrode assembly for an electrodecatheter system generally comprises a plurality of struts each extendingfrom a proximal end to a distal end of the electrode assembly. Eachstrut has a longitudinally extending proximal leg, a longitudinallyextending distal leg, and a center segment extending between andinterconnecting the proximal leg and the distal leg. The center segmentof each of the struts has a corresponding electrode thereon. Theelectrode assembly is configurable between a collapsed configuration andan expanded configuration, with the electrodes being transversely spacedfrom the longitudinal axis of the electrode assembly a greater distancein the expanded configuration than in the collapsed configuration.

In still another embodiment, an electrode assembly for an electrodecatheter system generally comprises a plurality of struts each extendingfrom a proximal end to a distal end of the electrode assembly. Eachstrut has a riser element disposed thereon intermediate the proximal endand the distal end of the electrode assembly. The electrode assembly isconfigurable between a collapsed configuration and an expandedconfiguration. In the expanded configuration the riser element of eachstrut extends transversely outward from the longitudinal axis of theelectrode assembly a greater distance than any other point along therespective strut, with each strut further having an electrode disposedon the respective riser element.

In still another embodiment, an electrode assembly for an electrodecatheter system generally comprises a plurality of struts each extendingfrom a proximal end to a distal end of the electrode assembly and eachhaving a corresponding electrode thereon. The electrode assembly isconfigurable between a collapsed configuration and an expandedconfiguration, with the electrodes being transversely spaced from thelongitudinal axis of the electrode assembly a greater distance in theexpanded configuration than in the collapsed configuration. In thecollapsed configuration at least one of the struts has a generallyconcave segment extending lengthwise along the strut intermediate theproximal and distal ends of the electrode assembly.

The foregoing and other aspects, features, details, utilities andadvantages of the present disclosure will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a catheter systemincluding a handle, a catheter and an electrode assembly having multipleelectrodes, with the electrode assembly being in what is referencedherein as a collapsed configuration.

FIG. 2 is a side elevation of the catheter system of FIG. 1, with theelectrode assembly being in what is referenced herein as an expandedconfiguration resulting from rotation of a rotatable actuator.

FIG. 3 is a perspective view of the electrode assembly of FIG. 1 with aplurality of struts carrying the multiple electrodes, the electrodeassembly being in its collapsed configuration.

FIG. 4 is a longitudinal cross-section of the electrode assembly of FIG.3.

FIG. 5 is a perspective view of the electrode assembly similar to FIG. 3but illustrating the electrode assembly in its expanded configuration.

FIG. 6 is an enlarged perspective view of a distal end of the electrodeassembly of FIG. 3.

FIG. 7 is an enlarged perspective view of a proximal end of theelectrode assembly of FIG. 3.

FIG. 8 is an enlarged top plan view of another embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 9 is an enlarged top plan view of a third embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 10 is an enlarged top plan view of a fourth embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 11 is an enlarged top plan view of a fifth embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 12 is an enlarged top plan view of a sixth embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 13 is an enlarged top plan view of a seventh embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 14 is an enlarged top plan view of an eighth embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 15 is an enlarged top plan view of a ninth embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 16 is an enlarged top plan view of a tenth embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 17 is an enlarged top plan view of an eleventh embodiment of ahinge suitable for use with the electrode assembly of FIG. 3.

FIG. 18 is an enlarged top plan view of a twelfth embodiment of a hingesuitable for use with the electrode assembly of FIG. 3.

FIG. 19 is an enlarged top plan view of a thirteenth embodiment of ahinge suitable for use with the electrode assembly of FIG. 3.

FIG. 20 is an enlarged top plan view of a fourteenth embodiment of ahinge suitable for use with the electrode assembly of FIG. 3.

FIG. 21 is a schematic view of the electrode assembly of FIG. 3 at onestage of manufacturing thereof at which the electrode assembly is in theform of a tube, with the tube being in a longitudinally opened and laidflat orientation for illustrative purposes.

FIG. 22 is a transverse cross-section taken through a center segment ofone strut of the electrode assembly of FIG. 3.

FIG. 23 is a transverse cross-section taken through a center segment ofanother embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 24 is a transverse cross-section taken through a center segment ofa third embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 25 is a transverse cross-section taken through a center segment ofa fourth embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 26 is a transverse cross-section taken through a center segment ofa fifth embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 27 is a transverse cross-section taken through a center segment ofa sixth embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 28 is a transverse cross-section taken through a center segment ofa seventh embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 29 is a transverse cross-section taken through a center segment ofan eighth embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 30 is a transverse cross-section taken through a center segment ofa ninth embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 31 is a transverse cross-section taken through a center segment ofa tenth embodiment of a strut suitable for use with the electrodeassembly of FIG. 3.

FIG. 32 is side elevation of a second embodiment of an electrodeassembly, having a pair of struts, with the electrode assembly beingillustrated in its collapsed configuration.

FIG. 33 is a side elevation of the electrode assembly of FIG. 32illustrated in its expanded configuration.

FIG. 34 is a side elevation of a third embodiment of an electrodeassembly, having a pair of struts, with the electrode assembly beingillustrated in its collapsed configuration.

FIG. 35 is a side elevation of the electrode assembly of FIG. 34illustrated in its expanded configuration.

FIG. 36 is a side elevation of a fourth embodiment of an electrodeassembly, having a pair of struts, with the electrode assembly beingillustrated in its collapsed configuration.

FIG. 37 is a side elevation of a fifth embodiment of an electrodeassembly, having a pair of struts, with the electrode assembly beingillustrated in its collapsed configuration.

FIG. 38 is a side elevation of a sixth embodiment of an electrodeassembly, having a pair of struts, with the electrode assembly beingillustrated in its collapsed configuration.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE DISCLOSURE

Referring now to the drawings, and in particular to FIGS. 1 and 2, oneembodiment of a catheter system 21 includes a flexible catheter 23, ahandle 25 to which the catheter is connected, and a conductor assembly27 for electrically connecting the catheter system to a suitable powersupply (not shown). As one example, the catheter system 21 illustratedand described herein is suitably constructed for use as an ablationsystem, such as a renal or heart ablation system. More particularly, theillustrated catheter system 21 is a multi-electrode renal denervationsystem. One example of such a catheter system 21 is currently made bySt. Jude Medical, Inc. under the trade name EnligHTN. General operationof a multi-electrode renal denervation system is known to those of skillin the art and is not described further herein except to the extentnecessary to describe the present embodiments. It is also understoodthat the catheter system 21 may be used for any other suitable treatmentor purpose without departing from the scope of this disclosure.Additionally, while the catheter system 21 is illustrated and describedherein as including a flexible catheter 23, the system may furtherinclude other components used, for example, to guide the flexiblecatheter into the patient—such as, without limitation, a relatively morerigid guide catheter (not shown), or an over-the-wire system (notshown).

The catheter 23 includes an elongate, flexible hollow shaft 29 connectedto the handle 25 at or near a proximal or rear end of the catheter shaft(not shown because it is hidden by a connector at the front end of thehandle 25), and an electrode assembly 33 disposed at or near a distal orfront end 35 of the catheter shaft. It is understood, however, that theelectrode assembly 33 may be disposed anywhere along the catheter shaft29 intermediate the proximal end and the distal end 35 thereof withoutdeparting from the scope of this disclosure. As used herein, the termsproximal and front, and distal and rear, are used with reference to theorientation of the catheter system 21 illustrated in the variousdrawings and for the purpose of describing the various embodiments setforth herein, and are not intended as limiting the catheter system andrelated components to having any particular orientation upon assembly orduring operation thereof. In particular, the terms proximal and rearrefer to a longitudinal position that is relatively nearer to the handle25 while the terms distal and front refer to a longitudinal positionthat is relatively farther from the handle.

The illustrated electrode assembly 33 is in the form of what may bereferred to as an electrode basket and is suitably configurable betweena collapsed configuration (FIGS. 1 and 3) for maneuvering andpositioning the electrode assembly in the patient, and an expandedconfiguration (FIGS. 2 and 5) for operation of the electrode assembly toperform a desired procedure such as an ablation procedure. An annular(e.g., ring-shaped) actuator 37 is mounted on the handle 25 for rotationrelative thereto and is operatively connected to the electrode assembly33 for selectively configuring the electrode assembly between itscollapsed and expanded configurations. It is understood that anothersuitable actuator (e.g., slide, push button, lever, etc.) may be usedinstead of the rotating actuator 37 to selectively configure theelectrode assembly 33 without departing from the scope of thisdisclosure. In some embodiments, the electrode assembly 33 may beselectively adjustable between an infinite number of configurations(e.g., degrees of expansion) between its collapsed and expandedconfigurations using the actuator 37.

A control line, such as a suitable cable or pull wire 41 (FIGS. 3 and 4)extends from the electrode assembly 33 within the hollow catheter shaft29 and into the handle 25 for operative connection with the actuator tothereby operatively connect the actuator 37 with the electrode assembly.In some embodiments, two or more pull wires, cables or other suitablecontrol lines may be used for selectively configuring the electrodeassembly 33. It is also understood that the control line 41 may be anysuitable control line other than a pull wire, such as a cable, string,tie, compression member or other suitable control to operatively connectthe electrode assembly 33 to the actuator 37. In other embodiments, anysuitable conventional manner for actuating or otherwise selectivelyconfiguring the electrode assembly 33 may be used. A suitable twistedelectrical wire bundle (not shown) also extends through the hollowcatheter shaft 29 from the handle to the electrode assembly to deliverpower to the electrode assembly.

With reference now to FIG. 3, the electrode assembly 33 has a proximalend 51 at which the assembly is connected to the catheter shaft 29(e.g., to the distal end 35 of the catheter shaft in the embodiment ofFIGS. 1 and 2), a distal end 53 that in the illustrated embodiment alsodefines a distal end, or tip, of the catheter 23, and a longitudinalaxis X. The illustrated electrode assembly 33 comprises a set of fourstruts 55 a-d, extending coextensively with each other from the proximalend 51 to the distal end 53 of the electrode assembly incircumferentially equal spaced relationship with each other about thelongitudinal axis X of the electrode assembly. In other embodiments, theelectrode assembly 33 may comprise more or less than four struts 55 a-d(see, e.g., the embodiments of FIGS. 32-38) without departing from thescope of this disclosure. It is also contemplated that the struts 55 a-dmay be other than equally spaced from each other circumferentially,and/or the struts may be other than coextensive with each other, andremain within the scope of this disclosure.

Each of the struts 55 a-d carries at least one electrode 57 disposed ata respective longitudinal position along the strut, i.e., at arespective longitudinal distance along the longitudinal axis X from theproximal end of the electrode assembly. In the embodiment of FIG. 3,each of the electrodes 57 is at a different longitudinal position. It isunderstood that the electrodes 57 may be at longitudinal positions otherthan those shown in FIG. 3. In other embodiments, two, three or all ofthe electrodes 57 may instead be at the same longitudinal position. Itis also understood that multiple electrodes 57 may be carried by any oneor all of the struts 55 a-d, e.g., with the electrodes on any givenstrut spaced longitudinally from each other along the strut. While notshown in FIG. 3, a respective suitable sheathing or sleeve, constructedof a polymeric material, circumferentially encloses each of the struts55 a-d along their respective lengths. The segment of the control line41 that extends from the proximal end to the distal end of the electrodeassembly may likewise be circumferentially enclosed by a suitablepolymeric sheathing or sleeve.

At the distal end 53 of the electrode assembly 33, the struts 55 a-dterminate at, and in one embodiment for making the electrode assemblyare formed integrally with, a connecting ring 61 (as best illustrated inFIGS. 4 and 6) having a central opening 63 that is coaxial with thelongitudinal axis X of the electrode assembly. In the illustratedembodiment, multiple holes 65 are formed in the sidewall of theconnecting ring 61 in spaced relationship with each other about thecircumference of the connecting ring and are open to the central opening63 of the connector. In other embodiments, however, the holes 65 may beomitted. Suitable polymeric sheathing (not shown) may surround theconnecting ring 61 to cover the holes 65 following assembly of theelectrode assembly 33. A blunt tip 67 includes a rounded head 71 havinga cylindrical body 69 extending longitudinally therefrom and beinggenerally hollow along its length such that the rounded head closes thedistal end of the body.

The control line 41 extends generally along the longitudinal axis X ofthe electrode assembly 33 through the body 69 of the tip 67 where it issecured to the tip by braising, adhesive, welding, soldering or othersuitable securement technique. The tip body 69 is sized in transversecross-section, e.g., outer diameter, to be received through and seatedwithin the central opening 63 of the connecting ring 61 with the head 71of the tip 67 abutting against the end of the connecting ring as seen inFIGS. 4 and 6. The holes 65 spaced about the circumference of theconnecting ring 61 allow a suitable adhesive to be supplied through theholes for securing the tip 67 on the connecting ring—thereby connectingthe distal end 53 of the electrode assembly 33 to the control line 41for operative connection with the actuator 37 on the handle 25. In otherembodiments, the struts 55 a-d may be retained at the distal end 53 ofthe electrode assembly 33 in another suitable manner and remain withinthe scope of this disclosure. It is also contemplated that the struts 55a-d and connecting ring 61 may be formed separate from each other andsubsequently secured together by any suitable securement technique.

Referring to FIGS. 4 and 7, at the proximal end 51 of the electrodeassembly 33, longitudinal end segments 59 of the struts 55 a-d areconnected to the catheter shaft 29 by a suitable bushing 81. The bushing81 includes a tubular cylindrical body 83 having a central opening 85through which the control line 41 extends from the catheter shaft 29 tothe electrode assembly 33. An annular flange 87 extends radially outwardfrom the longitudinally outer end of the bushing 81. The flange 87 hasfour slots 89 (corresponding to the respective longitudinal end segments59 of the struts 55 a-d) extending longitudinally therethrough radiallyoutward of the cylindrical body 83 of the bushing 81 and incircumferentially spaced relationship with each other. The longitudinalend segments 59 of the struts 55 a-d extend through the respective slots89 and along the outer surface of the cylindrical body 83 of the bushing81.

The body 83 of the bushing 81 (along with the longitudinal end segments59 of the struts 55 a-d) is fitted with a polyimide sleeve 91 filledwith suitable adhesive to secure the sleeve and longitudinal endsegments of the struts to the bushing. The bushing 81, struts 55 a-d andpolyimide sleeve 91 are inserted into the distal end 35 of the hollowcatheter shaft 29 and secured to the catheter shaft by suitable adhesiveto secure the proximal end 51 of the electrode assembly 33 to the distalend of the catheter shaft. It is understood that the struts 55 a-d maybe connected to the catheter shaft 29 by any other suitable connectionthat allows the electrode assembly 33 to function in the mannerdescribed herein.

The electrode assembly 33 thus has a length defined by the distancealong the longitudinal axis X from the proximal end 51 to the distal end53 of the electrode assembly. To configure the electrode assembly 33from its collapsed configuration (e.g., as illustrated in FIGS. 1 and 3)to its expanded configuration (e.g., as illustrated in FIGS. 2 and 5),rotation of the actuator 37 relative to the handle 25 operatively pullson the control wire 41 to thereby pull the tip (i.e., the distal end 53)of the electrode assembly toward the proximal end 51 of the electrodeassembly along the longitudinal axis X thereof. As the distance betweenthe distal end 53 and the proximal end 51 of the electrode assembly 33is shortened (i.e., as the length of the electrode assembly decreases),the struts 55 a-d are longitudinally compressed and thus forced to bend,or flex transversely outward away from the longitudinal axis X of theelectrode assembly to form the expanded configuration of the electrodeassembly. As used herein, the expanded configuration of the electrodeassembly refers to any transverse movement of the struts 55 a-d outwardfrom the collapsed (e.g., initial or pre-set) configuration of theelectrode assembly, and may be variably adjusted. Accordingly, it isunderstood that in the expanded configuration the electrode assembly 33may be expanded more or less than as illustrated in the variousembodiments herein. It is also understood that the collapsedconfiguration is not intended to mean the most compressed form in whichthe electrode assembly 33 may be configured, but rather it refers to therelaxed configuration of the electrode assembly free from any externalcompression forces (such as when compressed to fit the electrodeassembly into a guide tube or lumen).

FIG. 21 illustrates one embodiment of a method for making the electrodeassembly 33 of FIGS. 1-7. A unitary tube 121 of a material havingsufficient strength and shape memory characteristics, such as Nitinol™,is used. The material or materials from which the tube 121 isconstructed, however, may be any other suitable material and remainwithin the scope of this disclosure. In FIG. 21, the tube 121 is cutlengthwise and laid flat for illustrative purposes. The desired patternof struts 55 a-d is laser cut into the tube 121. As illustrated in FIG.21, the tube 121 is initially longer than the length of the finishedelectrode assembly 33 (as illustrated, e.g., in FIG. 3). An alignmentmember 123 is formed on each strut 55 a-d during the laser cuttingprocess longitudinally outward of the ends of the struts near whateventually becomes the proximal end 51 of the electrode assembly 33.

Once the struts 55 a-d are formed in the tube 121, an initial slightamount of preset expansion is formed in the tube 121 as illustrated inFIG. 3 using an internal and external die assembly or other suitabletechnique and then heat setting the tube to give the tube shape itscollapsed (e.g., initial or preset) configuration. Such preset gives thestruts 55 a-d increased shaped memory and facilitates more predictablebending of the struts into the desired expanded configuration of theelectrode assembly. Following the heat setting, the tube 121 is cutadjacent the alignment members 123 to define the longitudinal endsegments 59 of the struts 55 a-d for connecting the struts to thebushing 81 and subsequently to the catheter shaft 29 in the mannerdescribed previously. The tip 67 is secured to the distal end 53 of theelectrode assembly 33 (e.g., to the connecting ring 61) in the mannerdescribed previously.

With reference back to FIGS. 3 and 4 as well as to FIG. 21, each of thestruts 55 a-d of the illustrated electrode assembly 33 is suitablyconfigured in at least the collapsed configuration of the electrodeassembly to have what is referred to herein as a proximal leg 103 a-d, adistal leg 105 a-d, and a center segment 106 a-d extending between andinterconnecting the proximal and distal legs of the strut. To facilitatepredictable bending of the struts 55 a-d, each strut includes a pair ofhinges 101 a-d, 102 a-d in longitudinally spaced relationship with eachother, i.e., with one hinge 101 a-d intermediate and interconnecting theproximal leg 103 a-d and the center segment 106 a-d of the strut and theother hinge 102 a-d intermediate and interconnecting the distal leg 105a-d and the center segment of the strut. In particular, with referenceto the strut 55 a in FIG. 3, the proximal leg 103 a extends from the onehinge 101 a to the proximal end of the electrode assembly 33 and thedistal leg 105 a extends from the other hinge 102 a to the connectingring 61 at the distal end of the electrode assembly.

In the illustrated embodiment, the proximal leg 103 a-d and the distalleg 105 a-d of each strut 55 a-d are of generally equal length. In otherembodiments, some of which are described later herein, the proximal leg103 a-d and the distal leg 105 a-d may be of unequal length. Also, inthe illustrated embodiment, each strut 55 a-d has a proximal leg 103a-d, central segment 106 a-d and distal leg 105 a-d of lengths equal tothe proximal leg, central segment and distal leg of each of the otherstruts so as to maintain symmetry of the electrode assembly 33. It isunderstood, though, that the respective lengths of the proximal leg 103a-d, center segment 106 a-d and distal leg 105 a-d of one strut may bedifferent from that of one or more of the other struts. The electrodes57 are disposed respectively on the center segment 106 a-d of eachcorresponding strut 55 a-d.

In the illustrated embodiment of FIGS. 3 and 21, the proximal leg 103a-d, the distal leg 105 a-d and the center segment 106 a-d each have auniform width along the respective lengths thereof, i.e., other thanwhere the proximal leg narrows to form the end segments 59 that connectto the bushing 81. However, it is contemplated that in other embodimentsthe proximal leg 103 a-d may have a non-uniform width, such as a widththat decreases continuously (i.e., tapers or narrows) from adjacent thehinge 101 a-d to the end segment 59. Alternatively, or additionally, thedistal legs 105 a-d may have a non-uniform width, such as a width thatdecreases continuously (i.e., tapers, or narrows) from adjacent thehinge 102 a-d to adjacent the connecting ring 61. In other embodiments,the width of each proximal leg 103 a-d and/or distal leg 105 a-d may betapered in another suitable manner. The width of each center segment 106a-d of each strut 55 a-d is generally uniform along its length. Eachstrut 55 a-d of the illustrated embodiment has a narrowed widthintermediate the center segment 106 a-d and the proximal leg 103 a-d todefine the hinge 101 a-d and another narrowed width intermediate thecenter segment and the distal leg 105 a-d to define the hinge 102 a-d.In the illustrated embodiment the width of each strut 55 a-d at thehinge 101 a-d is equal to the width of the strut at the other hinge 102a-d. However, in other embodiments the width of the strut 55 a-d at thehinge 101 a-d may be different from the width of the strut at the otherhinge 102 a-d and remain within the scope of this disclosure.

As used herein, the term “hinge” refers to any suitable intended, presetor predetermined point or zone of flexure or bending in the strut. Forexample, in the illustrated embodiment of FIG. 3, the hinges 101 a-d,102 a-d are each formed by generally U-shaped symmetrical cut-outs onopposite sides of each strut 55 a-d so that the strut material iscontinuous across the narrowed width of the strut. The rounded contourof each of the cut-outs reduces the stress at the hinge 101 a-d, 102 a-dupon bending of the strut 55 a-d.

In other embodiments, such as illustrated in FIGS. 9-11, the hinges 101a-d, 102 a-d (only one such hinge being illustrated) may be formed bysymmetrical cut-outs that are other than generally U-shaped, such asgenerally V-shaped (FIG. 9), generally rectangular (FIG. 10), generallytrapezoidal (FIG. 11) or other suitable shape. It is also understoodthat one or both of the hinges 101 a-d, 102 a-d may alternatively beformed by one or more interior openings 107 disposed between the sideedges of the strut 55 a-d at the respective hinge so that the narrowedwidth of the strut at the hinge is defined by the combined widths of thetransverse webs 108 of strut material remaining on both sides of such anopening. For example, as illustrated in the alternative embodiments ofFIGS. 12 and 13, such an interior opening 107 may be circular, oval(FIG. 12), rectangular (FIG. 13) or other suitable shape. In thealternative embodiment of FIG. 14, the strut is widened at the hinge 101a-d, 102 a-d to accommodate an interior opening 107 having a generallyovate shape. FIGS. 15 and 16 illustrate another alternative embodimentin which each hinge 101 a-d, 102 a-d comprises opposed, symmetricalcut-outs along with one or more interior openings 107. In particular, inFIG. 15 a pair of generally diamond-shaped interior openings 107 areformed in each strut 55 a-d adjacent the longitudinally opposite ends ofthe opposed cut-outs, while in FIG. 16 a single elongated interioropening 107 extends lengthwise from adjacent one end of the opposedcut-outs to adjacent the opposite end of the opposed cut-outs. It iscontemplated that in other embodiments the opposed cut-outs may not besymmetrical.

FIGS. 17-20 illustrate additional alternative embodiments in which eachhinge 101 a-d, 102 a-d is formed by two or more slots or cuts 109extending transversely across the strut from opposite side edges of thestrut. For example, in FIG. 17, a series of three generally V-shapedcuts 109 are formed in the side edges of the strut 55 a-d—i.e., with twoof the V-shaped cuts extending from one side edge of the struttransversely across part of the strut and the other V-shaped cutextending from the opposite side of the strut transversely across partof the strut intermediate the other two V-shaped cuts. The cuts 109 maybe other than V-shaped in other embodiments. FIGS. 18, 19 and 20illustrate slots 111, each having a generally circular terminal end 113,extending transversely across part of the strut 55 a-d from oppositeside edges thereof. For example, two such slots 111 are illustrated inFIG. 18, three such slots are illustrated in FIG. 19 and four such slotsare illustrated in FIG. 20. It is understood that the number of slots111 may be less than two or greater than four within the scope of thisdisclosure. It is also understood that the slots 111 may be shaped otherthan as illustrated and remain within the scope of this disclosure.

It is also contemplated that in other embodiments one or both of thehinges 101 a-d, 102 a-d of each strut 55 a-d may be formed other than byforming cut-outs or slots in the struts. For example, in someembodiments one or all of the struts 55 a-d may be of uniform width andcross-section along its entire length, but have a pair of longitudinallyspaced preset bends or creases formed in the strut to respectivelydefine the hinges 101 a-d, 102 a-d. In still other embodiments, a hinge101 a-d, 102 a-d may be formed as a result of differing characteristics(e.g., transverse cross-section, thickness, width, etc.) between theproximal leg 103 a-d and the center segment 106 a-d and/or between thedistal leg 105 a-d and the center segment.

With reference to FIG. 5, by facilitating bending of the struts 55 a-dat the respective hinges 101 a-d, 102 a-d in the expanded configurationof the electrode assembly 33, the center segment 106 a-d of each struthas only a slight arch as illustrated, and in some embodiments may besubstantially flat along its length. As such, while the electrodes 57are at different longitudinal positions along the length of theelectrode assembly 33, the relatively little to no arch in each of thecenter segments 106 a-d of the struts 55 a-d facilitates concurrentapposition of all of the electrodes against the arterial wall whilestill accommodating a relatively compact configuration (due to thelongitudinally different positions of the electrodes) in the collapsedconfiguration of the electrode assembly, and more particularly when theelectrode assembly is further compressed transversely from the collapsedposition for maneuvering of the catheter within the patient—such aswithin a guide tube or lumen.

In some embodiments, at least the center segments 106 a-d, the proximaland distal legs 103 a-d, 105 a-d and/or the hinges 101 a-d, 102 a-d aresuitably configured to further facilitate the center segments 106 a-d ofthe struts 55 a-d having relatively little to no arch upon configurationof the electrode assembly 33 in its expanded configuration. For example,in one embodiment the center segments 106 a-d, and optionally theproximal and distal legs 103 a-d, 105 a-d may each have a width in therange of about 0.018 inches to about 0.038 inches. Additionally, oralternatively, the center segments 106 a-d, and optionally the proximaland distal legs 103 a-d, 105 a-d may each have a thickness in the rangeof about 0.003 inches to about 0.007 inches. It is understood, however,that the widths and/or thicknesses of the strut elements may be otherthan within the above ranges and remain within the present disclosure.

In addition to providing a relatively stiffened center segment, thehinges 101 a-d, 102 a-d may be relatively more flexible, such as byforming each hinge to have a width that is substantially less than thewidth of the center segments 106 a-d and the proximal and distal legs103 a-d, 105 a-d, to facilitate bending at the hinges instead of alongthe center segment. For example, relative to the range of widths setforth above for the center segments 106 a-d and the proximal and distallegs 103 a-d, 105 a-d, the hinges 101 a-d, 102 a-d may each have a widthin the range of about 0.008 inches to about 0.018 inches. It isunderstood, however, that the hinges 101 a-d, 102 a-d may have a greaterwidth than as set forth above, including a width equal to the width ofthe center segments 106 a-d, such as where the hinges are formed bypre-bending and heat setting the struts 55 a-d at the desired hingelocations.

In other embodiments, at least the center segments 106 a-d of the strutsand optionally the proximal and/or distal ends 103 a-d, 105 a-d may beconfigured, e.g., in transverse cross-section, to have an increasedstiffness (i.e., resistance to flexing or bending) relative to a strutthat is generally flat in transverse cross-section. For example, asillustrated best in FIG. 22, at least the center segment 106 a-d of eachof the struts 55 a-d of the electrode assembly 33 of FIG. 3 is generallyarcuate or cambered in transverse cross-section along the length of thecenter segment. More particularly, as seen in FIG. 3, each of the struts55 a-d has a uniform arcuate transverse cross-section along its entirelength, including the proximal and distal legs 103 a-d, 105 a-d of eachstrut.

However, it is understood that the center segment 106 a-d of each strut55 a-d may be configured in transverse cross-section different from theproximal and distal legs 103 a-d, 105 a-d such that the center segmenthas a stiffness that is greater than the stiffness of each of theproximal leg and the distal leg. In such an embodiment (not shown), thedifference in transverse cross-sectional configuration between thecenter segment 106 a-d and the proximal leg 103 a-d defines the onehinge 101 a-d while the difference in transverse cross-sectionalconfiguration between the center segment and the distal leg 105 a-ddefines the other hinge 102 a-d. It is understood that the proximal anddistal legs 103 a-d, 105 a-d may have the same transversecross-sectional configuration as each other, or they may have differenttransverse cross-sectional configurations, within the scope of thisdisclosure.

FIGS. 23-27 illustrate alternative transverse cross-sectionconfigurations of at least the center segment 106 a-d (and optionallythe proximal leg 103 a-d and/or the distal leg 105 a-d) of each strut 55a-d. For example, the transverse cross-section may be configured to bean almost closed circle (FIG. 23), semicircular (FIG. 24), circular(FIG. 25), generally C-shaped (FIG. 26), generally U-shaped (FIG. 27),generally V-shaped (FIG. 28), generally M-shaped or W-shaped (FIG. 29)or other suitable configuration.

In other embodiments, the electrode assembly 33 may further include astiffening element secured to or otherwise abutting at least the centralsegment 106 a-d (and, optionally, the proximal leg 103 a-d and/or thedistal leg 105 a-d) of each strut 55 a-d to increase the stiffnessthereof relative to a strut that lacks such a stiffening element. Forexample, in the illustrated embodiment of FIG. 30, the stiffeningelement comprises a relatively rigid wire 115 that may extendlongitudinally along all or part of the length of at least the centralsegment 106 a-d of each strut 55 a-d in abutting relationship with theinner surface of the strut. The wire 115 adds rigidity to the centralsegment 106 a-d of the strut 55 a-d to thereby increase its stiffness.In the alternative embodiment of FIG. 31, the stiffening elementcomprises a relatively rigid sheath 117 that circumferentially surroundsat least the central segment 106 a-d of each of the struts 55 a-d alongall or part of the length of the central segment. While in theillustrated embodiment the sheath 117 extends about the fullcircumference of the central segment 106 a-d of each strut 55 a-d, it iscontemplated that in other embodiments the sheath may extendcircumferentially about only a portion of the circumference of thecentral segment. It is also understood that the stiffening element maybe any suitable stiffening element other than the wire of FIG. 30 or thesheath of FIG. 31. It is further understood that the stiffening elementmay further extend along all or part of the proximal leg 103 a-d and/orthe distal leg 105 a-d of each strut 55 a-d and remain within the scopeof this disclosure.

With reference now to FIGS. 32 and 33, another embodiment of anelectrode assembly 233 is illustrated as having a pair of struts 255 a,b instead of the four struts 55 a-d described in the previousembodiments. It is understood, however, that the electrode assembly 233of this embodiment may have more than two struts 255 a, b. As in theprevious embodiments, each of the struts 255 a, b of this embodiment hasa proximal leg 303 a, b, a distal leg 305 a, b and a center segment 306a, b extending longitudinally between and interconnecting the proximaland distal legs. The one strut 255 a has a hinge 301 a intermediate andinterconnecting the proximal leg 303 a and the center segment 306 a, andanother hinge 302 a intermediate and interconnecting the distal leg 305a and the center segment. The other strut 255 b has a hinge 302 aintermediate and interconnecting the proximal leg 303 b and the centersegment 306 b, and another hinge 302 b intermediate and interconnectingthe distal leg 305 b and the center segment 306 b. The hinges 301 a, b,302 a, b may be configured in accordance with any of the hingeconfigurations illustrated and described herein.

Additionally, a pair of electrodes 257 is disposed on the center segment306 a, b of each of the struts 255 a, b of this embodiment. In otherembodiments there may be a single electrode 257 on each of the struts255 a, b, or there may be more than two electrodes on each of thestruts. As best seen in FIG. 32, the electrodes 257 are disposed on thestruts 255 a, b at different longitudinal positions (i.e., differentlongitudinal distances from the proximal end of the electrode assembly233) so that in the collapsed configuration of the electrode assemblythe electrodes on one strut are at different longitudinal positions thanthe electrodes on the other strut. This arrangement facilitatescircumferentially compressing the electrode assembly 233 down to asmaller cross-section beyond that of the preset collapsed configurationof FIG. 32 to facilitate positioning of the electrode assembly in aguide tube or lumen.

In this embodiment, for each strut 255 a, b the length of the proximalleg 303 a, b is different from the length of the distal leg 305 a, b.For example, referring to the strut 255 a, the proximal leg 303 athereof is shorter than the distal leg 305 a of the strut. Additionally,the length of the proximal leg 303 a of one strut 255 a is differentfrom the length of the proximal leg 303 b of the other strut 255 b. Inthe illustrated embodiment, for example, the proximal leg 303 a of theone strut 255 a is shorter than the proximal leg 303 b of the otherstrut 255 b. Also in the illustrated embodiment, the correspondingdistal legs 305 a, b of the struts 255 a, b are of different lengths. Inparticular, the distal leg 305 a of the one strut 255 a (having theshorter proximal leg 303 a) is longer than the distal leg 305 b of theother strut 255 b. Accordingly, the center segments 306 a, b of thestruts 255 a, b are of a generally equal length. It is contemplated thatin other embodiments the center segments 306 a, b of the struts 255 a, bmay be of different lengths. In such embodiments the proximal legs 303a, b of the struts 255 a, b may be of different lengths while the distallegs 305 a, b are of a generally equal length, or the distal legs may beof different lengths while the proximal legs are of a generally equallength.

With the struts 255 a, b configured in this manner, upon configurationof the electrode assembly 233 to its expanded configuration the centersegments 306 a, b become longitudinally offset from each other asillustrated in FIG. 33 due to the different lengths of the respectiveproximal and distal legs 303 a, b, 305 a, b of the struts. Theelectrodes 257 on the struts 255 a, b, which are at differentlongitudinal positions in the collapsed configuration of the electrodeassembly 233 (FIG. 32) suitably become positioned at substantially thesame longitudinal position on each of the struts in the expandedconfiguration of the electrode assembly. In some ablation procedures itis advantageous to have the electrode(s) 257 on each strut 255 a, b atgenerally the same longitudinal position.

FIGS. 34 and 35 illustrate another embodiment of an electrode assembly433 having a pair of struts 455 a, b. It is understood, however, thatthe electrode assembly 433 of this embodiment may have more than twostruts 455 a, b. As in the previous embodiments, each of the struts 455a, b of this embodiment has a proximal leg 503 a, b, a distal leg 505 a,b and a center segment 506 a, b extending longitudinally between andinterconnecting the proximal and distal legs. Each strut 455 a, b alsohas a first hinge 501 a, b intermediate and interconnecting the proximalleg 503 a, b and the center segment 506 a, b, and a second hinge 502 a,b intermediate the distal leg 505 a, b and the center segment. Thehinges 501 a, b, 502 a, b may be configured in accordance with any ofthe hinge configurations illustrated and described herein.

In this embodiment, the center segment 506 a, b of each strut 455 a, bis configured to be generally concave as it extends lengthwise betweenthe proximal and distal legs 503 a, b, 505 a, b of the electrodeassembly 433. The concave configuration of the center segment 506 a, bmay be formed by including a hinge 507 a, b (having any of theconfigurations illustrated and described herein) intermediate thelongitudinal ends of the center segment 506 a, b, or by arching, orbowing the center segment transversely inward and heat setting thecenter segment in such an arched or bowed configuration to define thecollapsed configuration of the electrode assembly 433 as illustrated inFIG. 34.

Upon configuration of the electrode assembly 433 to its expandedconfiguration, as illustrated in FIG. 35, the proximal and distal legs503 a, b, 505 a, b of each strut 455 a, b are urged generallylongitudinally outward while the center segment 506 a, b is urged toun-bow to the extent that the center segment is less arched or bowed, oris more suitably only slightly arched or bowed, and is even moresuitably generally straight, or flat in the expanded configuration ofthe electrode assembly. While in the illustrated embodiment the hinges501 a, b, 502 a, b and 507 a, b are illustrated as being a relativelysharp bend, it is understood that in other embodiments one or more ofthe hinges may be formed as a more gradual or rounded configuration andremain with the scope of this disclosure. The corresponding electrodes457 on each strut 455 a, b are suitably at different longitudinalpositions, for reasons discussed previously herein, and in theillustrated embodiment they are each positioned on the respective centersegment 506 a, b of the strut.

FIGS. 36, 37 and 38 each illustrate further alternative embodiments ofan electrode assembly 633, each having a pair of struts 655 a, b. It isunderstood, however, that the electrode assemblies 633 of theseembodiment may have more than two struts. Each of the struts 655 a, bhas a riser element 673 intermediate the proximal and distal ends 651,653 of the electrode assembly 633 to facilitate a greater transverselyoutward point of contact of the electrodes against the arterial wallupon configuring the electrode assembly in its expanded configuration.In the illustrated embodiment of FIG. 36, for example, each strut 655 a,b has a pair of riser elements 673—with each riser element comprising agenerally trapezoidal configuration formed in the strut. Each riserelement may be formed in the respective strut using one or more hinges707 a, b. In this embodiment, one hinge 707 a, b is common to both ofthe riser elements 673 on each strut 655 a, b. It is understood,however, that the riser elements 673 on each strut 655 a, b may bediscrete from each other, e.g., without sharing a common hinge 707 a, b.The hinges 707 a, b may each be configured in accordance with any of thehinge configurations described previously herein. Upon configuration ofthe electrode assembly 633 to its expanded configuration (not shown),the riser element 673 of each strut 655 a, b defines the transverselyoutermost extent of the respective strut. The electrodes 657 of theelectrode assembly 633 are each disposed on a respective one of theriser elements 673 to facilitate apposition of the electrodes againstthe arterial wall.

In the embodiment illustrated in FIG. 37, the struts 655 a, b of theelectrode assembly 633 each include a single riser element 673 comprisedof a generally trapezoidal configuration formed in the strut. As in theprevious embodiment, each riser element 673 is suitably formed in therespective strut 655 a, b using suitable hinges 707 a, b. In theembodiment of FIG. 38, each of the struts 655 a, b is generally arcuatein the collapsed configuration of the electrode assembly 633. Each ofthe riser elements 673 comprises a generally rounded bump formed andpreset in the strut 655 a, b intermediate the proximal and distal endsof the electrode assembly 633. It is understood that the bump 673 may belarger or smaller than as illustrated in FIG. 38 without departing fromthe scope of this disclosure. It is also understood that the riserelements 673 may be formed in the struts 655 a, b of the electrodeassembly 633 in any other suitable manner and/or configuration withoutdeparting from the scope of this disclosure.

Although certain embodiments of this disclosure have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of this disclosure. All directionalreferences (e.g., upper, lower, upward, downward, left, right, leftward,rightward, top, bottom, above, below, vertical, horizontal, clockwise,and counterclockwise) are only used for identification purposes to aidthe reader's understanding of the present disclosure, and do not createlimitations, particularly as to the position, orientation, or use of thedisclosure. Joinder references (e.g., attached, coupled, connected, andthe like) are to be construed broadly and may include intermediatemembers between a connection of elements and relative movement betweenelements. As such, joinder references do not necessarily infer that twoelements are directly connected and in fixed relation to each other. Itis intended that all matter contained in the above description or shownin the accompanying drawings shall be interpreted as illustrative onlyand not limiting. Changes in detail or structure may be made withoutdeparting from the spirit of the disclosure as defined in the appendedclaims.

When introducing elements of the present disclosure or the preferredembodiment(s) thereof, the articles “a”, “an”, “the”, and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including”, and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above constructions withoutdeparting from the scope of the disclosure, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. An electrode assembly for an electrode cathetersystem, the electrode assembly having a longitudinal axis, a proximalend and a distal end, the electrode assembly comprising: first andsecond struts each extending from the proximal end to the distal end ofthe electrode assembly and having a corresponding electrode disposedthereon intermediate said proximal and distal ends of the electrodeassembly, wherein the electrode assembly is configurable between acollapsed configuration and an expanded configuration, the electrodesbeing transversely spaced from the longitudinal axis of the electrodeassembly a greater distance in the expanded configuration than in thecollapsed configuration, in the collapsed configuration the electrode onthe first strut being at a first longitudinal position intermediate theproximal and distal ends of the electrode assembly and the electrode onthe second strut being at a second longitudinal position intermediatethe proximal and distal ends of the electrode assembly and differentfrom the first longitudinal position of the electrode on the firststrut, in the expanded configuration the first longitudinal position ofthe electrode on the first strut being substantially equal to the secondlongitudinal position of the electrode on the second strut.
 2. Theelectrode assembly of claim 1 wherein each of the first and secondstruts comprises a longitudinally extending proximal leg, alongitudinally extending distal leg, and a center segment extendingbetween and interconnecting the proximal leg and the distal leg, thecorresponding electrodes being disposed on the center segment of eachrespective one of the first and second struts, the proximal leg of thefirst strut having a first length and the proximal leg of the secondstrut having a second length different from the first length of theproximal leg of the first strut.
 3. The electrode assembly of claim 2wherein the center segment of the first strut has a first length and thecenter segment of the second strut has a second length substantiallyequal to the first length of the center segment of the first strut. 4.The electrode assembly of claim 2 wherein the distal leg of the firststrut has a first length and the distal leg of the second strut has asecond length different from the first length of the distal leg of thefirst strut.
 5. The electrode assembly of claim 2 wherein each strutfurther comprises a first hinge interconnecting the proximal leg and thecenter segment, and a second hinge interconnecting the distal leg andthe center segment.
 6. An electrode assembly for an electrode cathetersystem, the electrode assembly having a longitudinal axis, a proximalend and a distal end, the electrode assembly comprising: a plurality ofstruts each extending from the proximal end to the distal end of theelectrode assembly, each strut comprising a longitudinally extendingproximal leg, a longitudinally extending distal leg, and a centersegment extending between and interconnecting the proximal leg and thedistal leg, the proximal leg and the distal leg of at least one of thestruts having a corresponding stiffness, the center segment of said atleast one of the struts having a stiffness greater than the stiffness ofeach of the proximal leg and the distal leg of said at least one of thestruts, the center segment of each of the struts having a correspondingelectrode thereon, wherein the electrode assembly is configurablebetween a collapsed configuration and an expanded configuration, theelectrodes being transversely spaced from the longitudinal axis of theelectrode assembly a greater distance in the expanded configuration thanin the collapsed configuration.
 7. The electrode assembly of claim 6wherein each strut comprises a first hinge interconnecting the centersegment with the proximal leg of said strut and a second hingeinterconnecting the center segment with the distal leg of said strut. 8.The electrode assembly of claim 6 wherein the center segment of eachstrut has a cross-section configuration, at least one of the proximalend and the distal end of each strut having a cross-sectionconfiguration that is different from the cross-section configuration ofthe center segment.
 9. The electrode assembly of claim 8 wherein thecenter segment of each strut has a cross-section configuration selectedfrom the group comprising: cambered, semicircular, circular, almostclosed semicircular, C-shaped, U-shaped, V-shaped, W-shaped andM-shaped.
 10. The electrode assembly of claim 6 further comprising, foreach strut, a respective stiffening element at least one of on andabutting at least the center segment of the strut to increase thestiffness thereof.
 11. The electrode assembly of claim 7 wherein thestrut is generally uniform in cross-section along its length, the firstand second hinges being heat-set hinges in which each strut is pre-bentat each of the first and second hinges to define the collapsedconfiguration of the electrode assembly.
 12. The electrode assembly ofclaim 6 wherein each electrode is disposed on a respective strut at alongitudinal distance from the proximal end of the electrode assembly,the longitudinal distance of one electrode being different from thelongitudinal distance of at least one other electrode, in the expandedconfiguration of the electrode assembly the electrodes beingtransversely spaced from the longitudinal axis of the electrode assemblyapproximately the same distance.
 13. An electrode assembly for anelectrode catheter system, the electrode assembly having a longitudinalaxis, a proximal end and a distal end, the electrode assemblycomprising: a plurality of struts each extending from the proximal endto the distal end of the electrode assembly, each strut comprising alongitudinally extending proximal leg, a longitudinally extending distalleg, and a center segment extending between and interconnecting theproximal leg and the distal leg, the center segment of each of thestruts having a corresponding electrode thereon, wherein the electrodeassembly is configurable between a collapsed configuration and anexpanded configuration, the electrodes being transversely spaced fromthe longitudinal axis of the electrode assembly a greater distance inthe expanded configuration than in the collapsed configuration.
 14. Theelectrode assembly of claim 13 wherein each strut comprises a firsthinge interconnecting the center segment with the proximal leg of saidstrut and a second hinge interconnecting the center segment with thedistal leg of said strut.
 15. The electrode assembly of claim 13wherein, for at least one of the struts, the center segment has astiffness, the proximal leg has a stiffness different from the stiffnessof the center segment and the distal leg has a stiffness different fromthe stiffness of the center segment, the first hinge being defined bythe difference in stiffness between the center segment and the proximalleg and the second hinge being defined by the difference in stiffnessbetween the center segment and the distal leg.
 16. The electrodeassembly of claim 15 wherein, for at least one of the struts, the centersegment has a cross-section along its length, the proximal leg has across-section along its length and different from the cross-section ofthe center segment, and the distal leg has a cross-section along itslength and different from the cross-section of the center segment, thefirst hinge being defined by the difference in cross-section between thecenter segment and proximal leg, the second hinge being defined by thedifference in cross-section between the center segment and the distalleg.
 17. The electrode assembly of claim 13 wherein the first hinge isformed by at least one cut-out formed in the strut between the centersegment and the proximal leg and the second hinge is formed by at leastone cut-out formed in the strut between the center segment and thedistal leg.
 18. The electrode assembly of claim 13 wherein the strut hasopposed side edges, each of the first and second hinges being defined byat least two transversely extending slots formed in the opposed sideedges, wherein for each of the first and second hinges at least one ofthe slots extends transversely from one of the side edges and terminatesprior to the opposite side edge, and at least one other one of the slotsextends transversely from the opposite side edge and terminates prior tosaid one of the side edges, the slots being longitudinally spaced fromeach other at the respective first and second hinges.
 19. The electrodeassembly of claim 13 wherein the proximal leg of at least one strut hasa first length and the proximal leg of at least one other strut has asecond length different from said first length
 20. The electrodeassembly of claim 13 wherein the center segment of the at least onestrut has a first length and the center segment of the at least oneother strut has a second length substantially equal to the first lengthof the center segment of the at least one strut.
 21. An electrodeassembly for an electrode catheter system, the electrode assembly havinga longitudinal axis, a proximal end and a distal end, the electrodeassembly comprising: a plurality of struts each extending from theproximal end to the distal end of the electrode assembly, each struthaving a riser element disposed thereon intermediate the proximal endand the distal end of the electrode assembly, the electrode assemblybeing configurable between a collapsed configuration and an expandedconfiguration, in the expanded configuration the riser element of eachstrut extending transversely outward from the longitudinal axis of theelectrode assembly a greater distance than any other point along therespective strut, each strut further having an electrode disposed on therespective riser element.
 22. The electrode assembly of claim 21 whereineach riser element is located a longitudinal distance from the proximalend of the electrode assembly, the riser element of one strut being at alongitudinal distance that is different from the longitudinal distanceof the riser element of at least one other strut.
 23. The electrodeassembly of claim 21 wherein the electrode assembly has a length fromits proximal end to its distal end, the length of the electrode assemblydecreasing upon configuration of the electrode assembly from itscollapsed configuration to its expanded configuration.
 24. The electrodeassembly of claim 21 wherein the struts are formed integrally with eachother.
 25. The electrode assembly of claim 21 in combination with thecatheter system, the catheter system comprising a handle, an elongateshaft extending from the handle, the electrode assembly, and an actuatorassociated with the handle and operatively connected to the electrodeassembly for selectively configuring the electrode assembly from itscollapsed configuration to its expanded configuration.
 26. An electrodeassembly for an electrode catheter system, the electrode assembly havinga longitudinal axis, a proximal end and a distal end, the electrodeassembly comprising: a plurality of struts each extending from theproximal end to the distal end of the electrode assembly and each havinga corresponding electrode thereon, wherein the electrode assembly isconfigurable between a collapsed configuration and an expandedconfiguration, the electrodes being transversely spaced from thelongitudinal axis of the electrode assembly a greater distance in theexpanded configuration than in the collapsed configuration, in thecollapsed configuration at least one of the struts having a generallyconcave segment extending lengthwise along the strut intermediate theproximal and distal ends of the electrode assembly.
 27. The electrodeassembly of claim 26 wherein in the expanded configuration said segmentof the strut is less concave than in the collapsed configuration of theelectrode assembly.
 28. The electrode assembly of claim 26 wherein inthe expanded configuration said segment of the strut is generally flatalong its length.
 29. The electrode assembly of claim 26 wherein said atleast one of the struts comprises a proximal leg, a distal leg and acentral segment extending between and interconnecting the proximal legand the distal leg, the central segment being generally concave as itextends lengthwise intermediate the proximal and distal legs in thecollapsed configuration of the electrode assembly.